import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
n = ni()
m = ni()
s = [input() for j in range(m)]

def saiki(f, d):
    if len(f) <= 1:
        return True
    if d == m:
        return False
    a = []
    b = []
    for i in f:
        if s[d][i] == "0":
            a.append(i)
        else:
            b.append(i)
    return saiki(a, d+1) & saiki(b, d+1)

if saiki(list(range(n)), 0):
    Yes()
else:
    No()